It has been suggested that during instrumental learning, animals are likely to react emotionally to the reinforcer. They may in addition react emotionally to their own achievements. These reactions are of interest with regard to the animals’ capacity for self-awareness. Therefore, we devised a yoked control experiment involving the acquisition of an operant task. We aimed to identify the emotional reactions of young cattle to their own learning and to separate these from reactions to a food reward. Twelve Holstein–Friesian heifers aged 7–12 months were divided into two groups. Heifers in the experimental group were conditioned over a 14-day period to press a panel in order to open a gate for access to a food reward. For heifers in the control group, the gate opened after a delay equal to their matched partner’s latency to open it. To allow for observation of the heifers’ movements during locomotion after the gate had opened, there was a 15m distance in the form of a race from the gate to the food trough. The heart rate of the heifers, and their behaviour when moving along the race towards the food reward were measured. When experimental heifers made clear improvements in learning, they were more likely than on other occasions to have higher heart rates and tended to move more vigorously along the race in comparison with their controls. This experiment found some, albeit inconclusive, indication that cattle may react emotionally to their own learning improvement. Introduction Emotional responses to stress exposure are greater when the stressful stimuli are not controllable, than when the subject can learn to control them (Drugan et al., 1997). In the 204 K. Hagen, D.M. Broom / Applied Animal Behaviour Science 85 (2004) 203–213 absence of fear or pain, is it possible that the ability to control something might in itself be rewarding? Dogs that are trained to assist people with severe disabilities in everyday tasks, have been noticed to perform at high levels of excitement, reliability and versatility when they have learned to experience task solving as intrinsically rewarding (N. Bondarenko, personal communication). During a previously conducted learning experiment with cattle we remarked increased excitement and possible signs of pleasure during the learning process (Hagen and Broom, 2003). Thus, animals might not only get excited about, for instance, the expectation of a reward, but also about realising that they themselves to some extent control the delivery of a reward. In other words, if they develop an understanding of a causal relationship in which they are the agents, this might be exciting to them. If this were the case, their emotional reactions in a situation where they learned a causal relationship should be different from their reactions in a situation where they just learned to expect something. The difference might occur either specifically during the process of understanding, or it might be retained after a task has been acquired. To investigate the occurrences of such differences, we designed a yoked control learning experiment.